Returns the index of the first invitation on a given day to which the player has not responded
See also Calendar functions.
monthOffset- Month to query relative to the calendar's currently displayed month (i.e. 0 for current month, 1 for next month, -1 for previous month) (
day- Day of the month to query (
index- Index of the event on the given day (from 1 to CalendarGetNumDayEvents()) (